This invention relates to a method for differentiating between elevator car door operation problems and landing door operation problems, based upon the number of runs to a landing at which the problem is sensed.
Known elevator diagnostic systems monitor a limited set of signals from the elevator system itself, such as door switches, door open limit switch, final limit switches, etc., and/or from external sensors such as temperature, vibration, noise, etc. These signals are analyzed and the combination and sequence of them is used to find those problems that require human intervention or a different mode of operation. A good elevator diagnostic system has to be able to detect the failures and point to the part or parts that are the origin of the failures.
One of the most complex mechanisms of an elevator is the door system, since it consists of a large number of mechanical and electrical components working together, and since it undergoes a very large number of operational cycles per unit of time. Elevator maintenance contracts typically require that the elevator be available some high fraction of the time. Many elevator service calls are related to the doors. The ability to identify a fault-causing component depends upon two factors: the amount and quality of the signals available to be used in diagnostics, and the accuracy of the diagnostic algorithms. It would be easy to separate elevator car door problems from elevator landing door problems if the landing door was operated independently; however, this would require each landing door to have its own door motor, position encoder, and motion control process loop. Such would be prohibitively expensive in any elevator system. Therefore, the way to monitor the landing doors is by taking advantage of the daily elevator door operation in providing normal service. This means utilizing all of the car door signals, including position encoder, motor, door open limit, door close limit, and so forth to discriminate, from an analysis thereof with respect to various floors, between abnormal operation originated by the car door from that originated by a landing door.
In a commonly owned, copending U.S. patent application, Ser. No. 09/898853, filed contemporaneously herewith, there is disclosed a method in which the distinction between car door and landing door problems is based on the number of landings at which the given problem is detected over a given period of time, such as at least 40% of the total number of floors having a problem indicating a car door problem, and less than 40% of the total number of floors having a problem indicating landing door problems at those landings. The accuracy of such method depends on traffic patterns that cannot be predicted in a manner sufficient to eliminate erroneous results. For example, an elevator serving ten floors with a diagnostic rule of xe2x80x9cat least three floorsxe2x80x9d may be only serving two floors because the rest are not occupied; then real car door problems will be identified as being in the landing doors when such is not the case.
Objects of the invention include provision of an improved methodology for discriminating between elevator car door problems and elevator landing door problems; an improved diagnostic methodology for detecting the source of elevator door operational problems; reducing the service time required for elevator door system service calls; and reducing elevator out-of-service time as a function of elevator door system problems.
According to the present invention, the number of runs of the elevator to each particular landing, at which any particular notable elevator door parameter is detected, is utilized to discriminate between elevator car door problems and elevator landing door problems. According to the invention, for any flag which may be indicative of a notable elevator door system condition or event, if at least some percentage (such as, for instance, 60%) of the total number of runs to landings resulted in such flag, and the flag occurred at more than one of the floors, then the problem is stated to be due to a car door component; otherwise, the problem is stated to be a landing door problem at all of the floors which have such flag.
Exemplary conditions which can be considered to be flags include: incorrect door opening or closing time, door slowing due to obstacles in the door path; an incorrect door fully-open or door fully-closed position; a mean door lock position error, or an incorrect variance in door lock position. Other conditions and event with which the invention may be used are disclosed in the aforementioned patent application.
Other objects, features and advantages of the present invention will become more apparent in the light of the following detailed description of exemplary embodiments thereof, as illustrated in the accompanying drawing.